Immigration reform: The five most important issues

John Moore / Getty Images

Clearly, any compromise on immigration will turn on demands to tighten border security to prevent further illegal migration. The problem is defining what a secure border looks like. There are about 18,500 U.S. Border Patrol agents assigned to the U.S.-Mexico border. That number is far higher than at any time in the last decade. Also, barriers have been constructed along nearly 700 miles of that border. Some lawmakers, such as Sen. John McCain (R-Ariz.), would like to see more high tech resources, including drones, used to patrol the border. Others insist that a commission be established to set standards for enhanced border security.

Clearly, any compromise on immigration will turn on demands to tighten border security to prevent further illegal migration. The problem is defining what a secure border looks like. There are about 18,500 U.S. Border Patrol agents assigned to the U.S.-Mexico border. That number is far higher than at any time in the last decade. Also, barriers have been constructed along nearly 700 miles of that border. Some lawmakers, such as Sen. John McCain (R-Ariz.), would like to see more high tech resources, including drones, used to patrol the border. Others insist that a commission be established to set standards for enhanced border security. (John Moore / Getty Images)

This is likely to be one of the thorniest issues facing lawmakers. At least half of the nation's farmworkers are in the United States illegally, according to surveys and other data. Any proposal will need to bridge the divide between growers and labor groups. Growers say they have difficulty finding U.S. workers willing to do the job, and want a guest worker program that allows them to hire seasonal labor. Union leaders and advocates caution that guest worker programs must provide better labor protections to guard against abuse and exploitation.

This is likely to be one of the thorniest issues facing lawmakers. At least half of the nation's farmworkers are in the United States illegally, according to surveys and other data. Any proposal will need to bridge the divide between growers and labor groups. Growers say they have difficulty finding U.S. workers willing to do the job, and want a guest worker program that allows them to hire seasonal labor. Union leaders and advocates caution that guest worker programs must provide better labor protections to guard against abuse and exploitation. (David Goldman / Associated Press)

Efforts to overhaul the nation's immigration system are underway, led by a bipartisan group of eight senators who are expected to unveil a bill after Congress returns from its recess. So far, these efforts have led to at least one significant pact between the AFL-CIO and the U.S. Chamber of Commerce for dealing with foreign low-skilled workers. While the deal represents a breakthrough, lawmakers must still reach agreement on other issues. Here are five that must still be addressed in a comprehensive immigration reform bill. -- Sandra Hernandez